In a semiconductor device, amorphous silicon was used previously to manufacture a semiconductor layer; but along with the continuous development of technology and the gradual improvement of requirements for device quality, the amorphous silicon with a relative lower mobility has been unable to meet the requirements for current semiconductor devices. For example, in a current large-sized liquid crystal display, when a drive frequency is 120 Hz, it requires that the mobility should reach 1 cm2/V.S. However, the mobility of a thin film transistor including the semiconductor layer made of the amorphous silicon is generally about 0.5 cm2V.S, which cannot meet the requirements.
In order to meet the above requirements, it has started to use a metal oxide (for example, amorphous IGZO) to manufacture the semiconductor layer. A thin film transistor including the semiconductor layer made of the metal oxide has a high mobility and a good homogeneity, so it can meet the requirements for electronic equipments.
However, the inventors find that the existing thin film transistors including a metal oxide semiconductor layer at least has a defect of unstable performance, which is illustrated as below.
As is well known, the metal oxide can be served as the semiconductor layer because it has a composition with a specific structure; once such structure is damaged, the performance of the metal oxide as the semiconductor layer is adversely influenced. In a semiconductor device, the semiconductor layer is always adjacent to an insulating layer; however, during a process of manufacturing an insulating layer in the prior art, a large amount of silicon dangling bonds are generated at a fractured surface, and these silicon dangling bonds absorb oxygen atoms in the metal oxide, which causes the structure of the metal oxide being as the semiconductor layer to change, thereby to influence the performance of the thin film transistor including the metal oxide semiconductor layer